The seagulls in Colwyn Bay are probably mutants. Embittered at not landing parts in Jurassic Park as baby pterodactyls, they vent their savage grievance on any holiday-makers foolish enough to leave their sarnies unguarded. Their natural cinematic home would have been Alfred Hitchock's 1963 film The Birds, but should any director be so foolish as to attempt to remake that classic, Rhos on Sea would make an excellent setting.

Yet on the second day of this match at Colwyn Bay even the massive gulls had to take second place in the avarice stakes to Lancashire's Ashwell Prince and Alviro Petersen. Then later, they may even have perched, corpulent and admiring, as Glen Chapple proved that this pitch was not quite so flat as to repel bowlers of timeless class.

Having already put on 324 for their side's third wicket when play began, Prince and Petersen extended their stand to a colossal 501 before Prince miscued a drive off David Lloyd and Andrew Salter took a good low catch running in from the long-off boundary. By that stage the partnership was already the highest in Lancashire's history, beating the mere 371 added by Frank Watson and Ernest Tyldesley against Surrey at Old Trafford in 1928. It was also the most conceded by Glamorgan for any wicket. Prince himself had hit 35 fours and seven sixes in a career-best 261 after a morning in which he had launched a cheerful assault on the car park behind the pavilion.

As Prince ambled back to the dressing room, tossing his bat in the air as he went and accompanied by Petersen's congratulations and hugs, he probably little knew that the partnership was only 22 runs shy of the third-wicket County Championship record, which is held by Michael Carberry and Neil McKenzie, or that it was the thirteenth most fruitful for any wicket in the first-class history.

Within half an hour Petersen was gone too, also caught in the deep off the frequently punished Lloyd and also for a career-best, in his case, 286. He and Prince had become the only Lancashire batsmen to have hit double-hundreds in the same innings. The total was then 625 for 4, which is really the sort of score one reads about rather than seeing first-hand.

All the same, there it was and after Steven Croft, the Lancashire captain, had thrashed another 57 runs in 51 balls, the declaration was applied with the score having moved on to 698 for 5, the fifth highest total in Lancashire's history. Between innings there were reports that Opta's statistician was frothing at the mouth in ecstasy. Such days do not come around very often for the number crunchers.

Many debates to this point had concerned the flatness of the pitch. Some Glamorgan players announced that they had never played cricket on anything quite like it. At the end of Lancashire's innings the scoreboard seemed to justify their view and it was even mooted that this pitch could give cricketers a standard by which the unresponsiveness of later surfaces could be assessed, a Colwyn Bay quotient to rank with the Richter and Beaufort scales.

Chapple put such talk into useful perspective. When it was announced on the first morning that Chapple, who is now 41, would be in Lancashire's side, there was a curious sigh of loving fondness from many in the crowd. So the happiness from the very many visiting supporters when Chapple moved one away just enough from Jacques Rudolph's loose defensive shot to clip the off stump needs little imagining. It was the beginning of a few overs to remember for Lancashire loyalists as they grab every chance they can to see Chapple in what must surely be the late autumn of his career.

Next over Colin Ingram was caught behind by Alex Davies for nought. After tea, Chris Cooke elected to leave a ball which was going to hit the off stump, and that is rarely a wise move. Chapple's figures at the end of his first spell read 11-4-27-3. For so many cricket fans, whatever their loyalties, his bowling counted for more than Petersen and Prince's stand. He had nagged away and coaxed assistance from a pitch which, hitherto, had seemed as hard as an airport runway.

Lancashire's bowlers were not finished, though, as they pressed for the victory that would make them even more prohibitive favourites for promotion. Will Bragg was leg before playing across a straight one from James Faulkner and the spinners Arron Lilley and Simon Kerrigan picked up the wickets of David Lloyd and Craig Meschede, both caught in the ring for 21 apiece during a long evening session.

Mark Wallace, the epitome of Welsh resistance, was still there on 39 and Graham Wagg, in this great season for him, made so bold as to hit Lilley's penultimate ball of the day for a six over long-on. Nonetheless, Glamorgan can rarely have been so far behind in a match and an early finish is clearly on the cards. This would be a shame for those who treasure the warm friendship, grassy banks and gentle charms of this ground.

The day finally ended with Petersen and Prince posing for snappers in front of a scoreboard rigged to record their partnership. Some of the resulting photographs will no doubt be auctioned at cricket dinners this winter; others will appear in county yearbooks, those annual chronicles of special weeks and afternoons of plenty.